High B/T Science Highlights
Observing growth processes in classical alloys is extremely difficult; scientists overcame this by studying quantum systems.
Controlled by electron interactions, the Mott transition is accompanied by a reduction in the volume of the atomic lattice.
Working with a solid form of helium at ultra-low temperatures, scientists observed a quantum phase separation that may shed light on analogous processes in classical systems like metal alloys.
Answered: Isotropic versus Anisotropic Transport in the Magnetic-Field-Induced Wigner-crystal state in 2D holes
Studies of the magnetotransport of strongly interacting 2D holes in high mobility, gated, GaAs quantum wells have been carried out a very low temperatures to search for possible anisotropy in the field-induced re-entrant insulating phase. The latter phase was observed in the resistivity at a magnetic field that depended on hole density but that was independent of current direction. This shows that the re-entrant insulating phase is not due to a proposed anisotropic stripe order, but is instead caused by Wigner crystallization.
High magnetic fields have been shown to induce strong electric polarizations in the doped organic quantum magnet, dichloro-tetrakis-thiourea, or DTN. The introduction of disorder in DTN leads to the formation of Bose glass states and the electric polarization is particularly enhanced at the transitions to the glass state.
New physics has had to be invoked to explain the existence of exotic quantum Hall states such as the n =5/2 and 7/2 states. Recent progress in fabrication of high-quality low-density samples allows one to probe these states in a new regime where the electron-electron interactions are strong. The results reveal the existence of anisotropic transport for n = 7/2 in a high-quality very dilute 2D electron system. The new behavior is attributed to a large Landau level mixing effect that perturbs the pairing stability of composite fermions in the dilute limit.
High precision NMR studies of dilute impurities in solid 4He have demonstrated the existence of an unexpected lattice relaxation at low temperatures (T<0.2K). This new effect is attributed to the quantum plasticity reported in studies of the elastic constants in the same temperature regime.
New research at the lab’s High B/T facility supports the proposal that the disordered ground state of terbium titanate is a quantum spin ice.
This experiment probes the nature of the 12/5 Fractional Quantum Hall state by using a hydraulic-driven rotator to tilt the two-dimensional system in a magnetic field.